1. Field of the Invention
The present invention relates to a method for producing bromomethylcyclopropane having a high purity. The bromomethylcyclopropane of the present invention is useful as a raw material of pharmaceutical products.
2. Discussion of the Related Art
Conventional methods for producing bromomethylcyclopropane, for example, include a method comprising reacting methanesulfonyl bromide with cyclopropylmethanol in the presence of a tertiary amine under heating (EP 565826), a method comprising reacting a dimethylsulfide-bromine complex with cyclopropylmethanol (Chem. Commun., p.212 (1973)), and a method comprising reacting phosphorus tribromide with cyclopropylmethanol (J. Am. Chem. Soc., p.2509 (1951)); however, in these methods, the ring-opening reaction of the cyclopropane ring or the isomerization thereof into bromocyclobutane is progressed, so that bromomethylcyclopropane with a high purity, as required for pharmaceutical usages, cannot be obtained.
A method for producing bromomethylcyclopropane at a high purity, suitable for pharmaceutical use, is known comprising brominating cyclopropylmethanol with triphenylphosphine-dibromide (J. Org. Chem., Vol.49, p.431 (1984) and WO 97/30958). However, this method is not appropriate for industrial practice, because it presents the disadvantages of having to use triphenylphosphine dibromide which is expensive and because the process generates large amounts of phosphorus waste.
Therefore, there is a need for an industrially advantageous method to produce bromomethylcyclopropane with a high purity, and at relatively low cost.